<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>检查替换后的词是否有效</title>
</head>
<body>
  <script>
    function fn(s) {
      let n = s.length / 2
      while (s.length != n) {
        n = s.length
        s = s.split('abc').join('')
      }
      if (s == '') return true
      return false
    }
    console.log(fn('abccba'))
  </script>
</body>
</html>